All vehicles and many other systems are today fitted with control panels that group together the interfaces necessary for the user to control functions as various as the audio system, the air-conditioning, the telephone, or navigation.
In motor vehicles, these control panels are installed in the central console in a virtually vertical plane and are thus accessible to and manipulable by both the driver and the front-seat passenger. The controls are various and suited to the controlled function. In particular, pushbuttons, rotary knobs, and touch screens are provided. From a structural point of view, the control panels are a stack of distinct layers forming a unit. They are generally constructed from a base attached to a printed circuit covered with an elastomer sheet against which is placed a decorative fascia provided with the various interfaces. The printed circuit comprises electrical circuit-breakers switched (i.e.—opened and closed) by the actuation of the pushbuttons. After the fashion of computer keyboards, the elastomer sheet, often formed of silicone, protects the printed circuit from dusts and other external elements. It is in addition provided with deformable domes placed at the locations of the pushbuttons so that a dome applies a slight return force to a button opposed to the depression, the force causing the button to return to its initial position after having been depressed. In addition, the sheet is indented or provided with openings or other cut-outs that allow the passage of electroluminescent diodes as well as mechanical elements of a knob or of a button from the decorative fascia to the printed circuit. For reasons of modularity linked to the selection of vehicle options, the elastomer sheet can be formed of a plurality of partial sheets juxtaposed on the printed circuit.
Water is one of the most undesirable external elements. Whether the cause of this is rain on a convertible, morning dew, the vigorous washing of the inside of the car, or the cause is an accidentally spilled drink, it is imperative that each control panel is provided with protections ensuring that the printed circuit is sheltered and does not risk being reached by a liquid. The elastomer sheet provides this liquid-proofing function in particular by means of a peripheral barrier slightly compressed against the inside face of the decorative fascia. However, due to the ageing and the differential expansion of the materials, the plurality of the sheets, the various shapes or the multiple cut-outs make this liquid-proofing function difficult to form reliably. Taking all these constraints into account it is important to propose an effective system for protection against liquids that can be adapted to various decorative fascia configurations.